[Raiiiden]

I have a few problems with my 328i 2011. On cold start it turns on then off and then I am able to start it after 2-3 starts, this doesn't happen anytime besides the morning. When I turn it on the car has a weird idle, it isn't terrible but it goes up and down rpms, not much like up to 1200, back to 1000, that area. When pressing the gas it feels inconsistent and when I rapidly accelerate to around 2500-3000 rpms the car shakes and when I get past to around 4000 it stops. Previous owner noted lower voltage on MAF sensor and Valvetronic motor. To me it sounds like a MAF sensor issue, but I'm not entirely sure as I haven't really worked on these cars much and I'm new. This could be a wiring issue as well, but I'd like opinions.

[YeldarbEfir]

My car has started sputtering/misfiring on hard acceleration after it's been idling for a few minutes.

[Raiiiden]

Originally Posted by YeldarbEfir

My car has started sputtering/misfiring on hard acceleration after it's been idling for a few minutes.

Honestly that could be so many things, I would recommend doing a scan

[lookalikehuuh]

Originally Posted by Raiiiden

I have a few problems with my 328i 2011. On cold start it turns on then off and then I am able to start it after 2-3 starts, this doesn't happen anytime besides the morning. When I turn it on the car has a weird idle, it isn't terrible but it goes up and down rpms, not much like up to 1200, back to 1000, that area. When pressing the gas it feels inconsistent and when I rapidly accelerate to around 2500-3000 rpms the car shakes and when I get past to around 4000 it stops. Previous owner noted lower voltage on MAF sensor and Valvetronic motor. To me it sounds like a MAF sensor issue, but I'm not entirely sure as I haven't really worked on these cars much and I'm new. This could be a wiring issue as well, but I'd like opinions.

What's interesting though is that on cold start your MAF is playing a somewhat lower role because the car is in open loop. Its not until the car has warmed up into closed loop that it really begins to matter what the MAF is sending.

You could theoretically unplug the MAF on your first cold start and the car will just run on its default strategy. That would eliminate the MAF as the root cause of the issue.

[Raiiiden]

Originally Posted by lookalikehuuh

What's interesting though is that on cold start your MAF is playing a somewhat lower role because the car is in open loop. Its not until the car has warmed up into closed loop that it really begins to matter what the MAF is sending.

You could theoretically unplug the MAF on your first cold start and the car will just run on its default strategy. That would eliminate the MAF as the root cause of the issue.

I'll test this tomorrow morning on the first cold start of the day. I was thinking about grabbing an extra valvetronic motor and maf sensor from picknpull this weekend, what years am I able to pull from? 2008-2013?

[Raiiiden]

Originally Posted by lookalikehuuh

What's interesting though is that on cold start your MAF is playing a somewhat lower role because the car is in open loop. Its not until the car has warmed up into closed loop that it really begins to matter what the MAF is sending.

You could theoretically unplug the MAF on your first cold start and the car will just run on its default strategy. That would eliminate the MAF as the root cause of the issue.

If not the MAF sensor, what could the culprits be on the start and idle?

[marvinstockman]

Fuel injector leak down.

[Raiiiden]

Originally Posted by marvinstockman

Fuel injector leak down.

I'll take a look, I appreciate it

[doit659]

I could be entire wrong but I think you might want to look at some more common issues before delving into a Valvetronic and MAF replacement.

I don't think it's a fuel injector issue, because that doesn't vary in bad idling at any RPM. Fuel injectors are an issue at any RPM. Your issue is a bit different.

I could be wrong, but if you disconnect the MAF to do any troubleshooting, I don't even think the car starts properly.

It COULD be your MAF sensor causing all the issues, but would be news to me.

I suggest to you to purchase a BMW-specific diagnostic tool to look at the codes on the car as a starting point before replacing components, esp. big jobs like the Valvetronic unit, which might be fine.

Personally, I think you have a vacuum leak.

Here is why I think so, subject to input from BMW technicians.

I had a sketchy MAF on a 325i but it never acted like what you are experiencing. But I dd have a vacuum leak which affects the entire aspiration of the engine.

So, I suggest you smoke test test the engine to make sure there is no leak and get a diagnostic tool if the smoke test is ok.

Thanks,

Robert

[Raiiiden]

Originally Posted by doit659

I could be entire wrong but I think you might want to look at some more common issues before delving into a Valvetronic and MAF replacement.

I don't think it's a fuel injector issue, because that doesn't vary in bad idling at any RPM. Fuel injectors are an issue at any RPM. Your issue is a bit different.

I could be wrong, but if you disconnect the MAF to do any troubleshooting, I don't even think the car starts properly.

It COULD be your MAF sensor causing all the issues, but would be news to me.

I suggest to you to purchase a BMW-specific diagnostic tool to look at the codes on the car as a starting point before replacing components, esp. big jobs like the Valvetronic unit, which might be fine.

Personally, I think you have a vacuum leak.

Here is why I think so, subject to input from BMW technicians.

I had a sketchy MAF on a 325i but it never acted like what you are experiencing. But I dd have a vacuum leak which affects the entire aspiration of the engine.

So, I suggest you smoke test test the engine to make sure there is no leak and get a diagnostic tool if the smoke test is ok.

Thanks,

Robert

I appreciate the insight. I will try to get a BMW-specific diagnostic tool this weekend and run it. I will get that smoke test done as well, but I'm pretty sure the previous owner fixed a small vacuum leak with the receipt of the visit but there could be two but it'd be weird if the shop didn't catch it.

[doit659]

Well, a BMW diagnostic is almost a necessary tool for BMW's that are going on 10+ years.

The tool will allow you to check BMW-specific codes which a typical generic OBDII device cannot read.

Also, these cars at this age start to have module and wiring harness issues just due to their age. Sometimes the issue is related to water damage or worse rodents eating wires, but sometimes the wiring connections in the harnesses just start to corrode. Unfortunate, but all too common, esp. if the car isn't kept in a pristine climate.

I could be wrong on this fact, but in my experience of owning many non-BMW cars and BMW's, BMW's have gaskets, plastic parts, and hoses that become brittle and decay way faster than cars like Corollas, etc.

And because a BMW is a far more performance engine than a Toyota generic, the BMW engine is way more sensitive to issues like vacuum leaks.

I could be wrong about your MAF sensor. I actually replaced one on a 2001 325i that I owned and was dead. I don't think they are too pricey. I tried to use some MAF spray to clean it but I ended up replacing it so maybe that is your issue.

Also, the BMW diagnostic tool will immediately help you if down the road you have issues with your ignition coils. The symptom is very obvious for this issue. You will start up the car and it will not idle without sputtering and will have no acceleration. It will run but barely. The diagnostic tool will pinpoint the cylinder with the bad coil.

Down the road, if you have an ignition coil issue, which your diagnostic will tell you, replace ALL of them. The tend to fail in a cascading pattern over time, and of course replace the plugs. I suggest using OEM coils and not some knock off crap. And good quality spark plugs. These parts are relatively inexpensive.

Regarding fuel injectors, I have not had issues on 2 cars ever with them. And thank God because they are CRAZY expensive like $250 a piece. There are some additives (which I use sparingly on my cars) that promise to clean them.

Do you have an oil pan gasket leak or yellowing head light covers? If so, I have a couple of solutions for you to consider.